2010-01-20_REVISION - C1981008 (5)

Home Browse Search

STATE OF COLORADO DIVISION OF RECLAMATION, MINING AND SAFETY Department of Natural Resources 1313 Sherman St., Room 215 Denver, Colorado 80203 Phone: (303) 866-3567 FAX: (303) 832-8106 COLORADO D I V I S I O N O F RECLAMATION MINING SAFETY INTEROFFICE MEMORANDUM Bill Ritter, Jr. Governor Harris D. Sherman Executive Director Ronald W. Cattany TO: Marcia Talvitie Division Director Natural Resource Trustee MA FROM: Mike Boulay DATE: January 20, 2010 SUBJECT: Western Fuels-Colorado, New Horizon Mine (Permit No. C-81-008), Permit Revision No. 6 (PR-6) As requested, I have reviewed Western Fuels-Colorado's (WFC's) PR-6 application. I have the following adequacy review comments. 1. WFC submitted a re-design for Pond 011 and new As-built Certification. WFC indicates on page 2.05.3(3)-14-2 that the drainage basins in both pre mine and post mine situations have changed. The pre mine drainage basin should remain constant. Please clarify and explain how the pre mine drainage basin situation has changed. 2. Pond 011 is being re-designed because it will receive a greater drainage area than originally designed due to the decision by WFC to eliminate Pond 010. There are no proposed changes to spillway configurations and only design input parameters will be modified. Both the Engineering and Hydrologic Design and the As-Built SEDCAD demonstration were re- submitted along with a new Map 2.05.3(3)-17 As-Built Certification. The revised application materials presented for design and as built configuration are consistent. Only one minor error was noted. The Stage Storage Curve on the new Pond 011, As Built shows an incorrect principal spillway elevation as compared to the SEDCAD runs and the approved As-Built Certification. Please check this elevation and make the necessary correction to Map 2.05.3(3) -17. 3. The revised text on page 2.05.3(3)-12-3 does not clearly explain why a revised pond design is necessary for Pond 012. In the third paragraph WFC states that "the post mine drainage area is larger than the pre-mine", but also in that same paragraph states "the pre-mine drainage area is 55.1 acres while the post mine area is 38.1 acres". This is inconsistent and it is unclear if the as built pond is sufficient to handle the revised drainage area. If the As- Built Certification is correct and no pond configuration changes are proposed then a new design would be unnecessary. Office of Office of Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines